5 Ways Birth Control Medication Can Affect Your Skin

It's called "the mask of pregnancy," but melasma affects plenty of women who aren't with child. It's characterized by dark patches that appear on skin that's exposed to sun -- often, the face. The "mask" part of the nickname comes from the fact that melasma usually covers the upper lip to the forehead and is symmetrical on both sides [source: PubMed Health].

Melasma is associated with female hormones, which is why pregnant women, women taking oral contraceptives and women on hormone replacement therapy (HRT) are most intimately acquainted with the brown discoloration.